[PATCH] net: ixp4xx_hss: fix duplicate HDLC netdev allocation

[PATCH] net: ixp4xx_hss: fix duplicate HDLC netdev allocation

[Haoxiang Li]

ixp4xx_hss_probe() allocates two HDLC netdevs. The first one is stored
in ndev, initialized, and registered with register_hdlc_device(). The
second one is stored in port->netdev and later used by the remove path
for unregister_hdlc_device() and free_netdev().

This means that the registered netdev is not the same object that is
unregistered and freed on remove. It also leaks the first allocation if
the second alloc_hdlcdev() call fails, and the first allocation is not
checked before ndev is used.

Older code allocated the HDLC netdev only once and stored the same object
in both the local variable and port->netdev. The buggy conversion split
this into two alloc_hdlcdev() calls. A later rename changed the local
variable name to ndev, but the underlying mismatch remained.

Fix this by allocating the HDLC netdev only once and assigning the same
object to port->netdev.

Fixes: 99ebe65eb9c0 ("net: ixp4xx_hss: move out assignment in if condition")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
---
 drivers/net/wan/ixp4xx_hss.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wan/ixp4xx_hss.c b/drivers/net/wan/ixp4xx_hss.c
index 720c5dc889ea..7f4645ff90aa 100644
--- a/drivers/net/wan/ixp4xx_hss.c
+++ b/drivers/net/wan/ixp4xx_hss.c
@@ -1487,11 +1487,11 @@ static int ixp4xx_hss_probe(struct platform_device *pdev)
 				     "unable to get CLK internal GPIO\n");
 
 	ndev = alloc_hdlcdev(port);
-	port->netdev = alloc_hdlcdev(port);
-	if (!port->netdev) {
+	if (!ndev) {
 		err = -ENOMEM;
 		goto err_plat;
 	}
+	port->netdev = ndev;
 
 	SET_NETDEV_DEV(ndev, &pdev->dev);
 	hdlc = dev_to_hdlc(ndev);
-- 
2.25.1

Re: [PATCH] net: ixp4xx_hss: fix duplicate HDLC netdev allocation

[Linus Walleij]

On Mon, Jun 22, 2026 at 6:30 AM Haoxiang Li <haoxiang_li2024@163.com> wrote:

> ixp4xx_hss_probe() allocates two HDLC netdevs. The first one is stored
> in ndev, initialized, and registered with register_hdlc_device(). The
> second one is stored in port->netdev and later used by the remove path
> for unregister_hdlc_device() and free_netdev().
>
> This means that the registered netdev is not the same object that is
> unregistered and freed on remove. It also leaks the first allocation if
> the second alloc_hdlcdev() call fails, and the first allocation is not
> checked before ndev is used.
>
> Older code allocated the HDLC netdev only once and stored the same object
> in both the local variable and port->netdev. The buggy conversion split
> this into two alloc_hdlcdev() calls. A later rename changed the local
> variable name to ndev, but the underlying mismatch remained.
>
> Fix this by allocating the HDLC netdev only once and assigning the same
> object to port->netdev.
>
> Fixes: 99ebe65eb9c0 ("net: ixp4xx_hss: move out assignment in if condition")
> Cc: stable@vger.kernel.org
> Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>

Reviewed-by: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij

Re: [PATCH] net: ixp4xx_hss: fix duplicate HDLC netdev allocation

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 22 Jun 2026 12:30:15 +0800 you wrote:
> ixp4xx_hss_probe() allocates two HDLC netdevs. The first one is stored
> in ndev, initialized, and registered with register_hdlc_device(). The
> second one is stored in port->netdev and later used by the remove path
> for unregister_hdlc_device() and free_netdev().
> 
> This means that the registered netdev is not the same object that is
> unregistered and freed on remove. It also leaks the first allocation if
> the second alloc_hdlcdev() call fails, and the first allocation is not
> checked before ndev is used.
> 
> [...]

Here is the summary with links:
  - net: ixp4xx_hss: fix duplicate HDLC netdev allocation
    https://git.kernel.org/netdev/net/c/db818b0e8af7

You are awesome, thank you!
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